Hi! I'm a 14 year old girl, and weigh 123ish pounds.. So obviously I'm a bit overweight.. I want to approach weight loss in a healthier way, so I am going to reduce my intake of food, and start to exercise. How much exercise will it take to lose 2 pounds a week? (My goal is to lose between 20-25 pounds)

What I forgot to mention is that my parents are not at all in support of me going on a diet. They do not think I need to lose any weight.. So the only way I can approach weight loss is by exercise. They are much more comfortable with this decision.

Thanks in advance!!